There are a large number of websites on the Internet and these websites publish a wide variety of information. A user terminal connected to the Internet accesses a website by specifying a URL (Uniform Resource Locator) of the website by a web browser, so that the user terminal can display a web page provided from the website. Thereby, a user of the user terminal can browse information posted on a web page provided from the website. Therefore, it is important for a provider of the information posted on the webpage to know the level of interest of the user (degree of interest) in the web page and the information posted thereon.
Conventionally, a method is known which determines the user's degree of interest on the basis of a browsing time of a web page (staying time in a web page). In this method, the longer the browsing time of the web page, the higher the user's degree of interest is determined to be. For example, Patent Document 1 discloses a technique for measuring an elapsed time by using transition of a web page as an end event and transmitting the elapsed time to a server as the browsing time of each web page.